This application claims the benefit under 35 U.S.C § 119(a) of Korean Patent Application No. 10-2004-0030454, filed on Apr. 30, 2004, the entire disclosure of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a paper feeding apparatus for a printer. More particularly, the present invention relates to a paper feeding apparatus for a printer including a double feed prevention unit to prevent two or more sheets of paper from being supplied simultaneously.
2. Description of the Related Art
In general, an image forming apparatus such as a printer or a copying machine includes a paper feeding apparatus. The paper feeding apparatus stores a plurality of sheets of paper and supplies a sheet of paper to a main body of the printer sequentially.
FIG. 1 shows a typical structure for an electrophotographic color image forming apparatus.
Referring to FIG. 1, the electrophotographic image forming apparatus includes a photosensitive drum 10 that is a photosensitive medium. Next, the apparatus includes a charging device 11 that charges the photosensitive drum 10, a laser scanning unit (LSU) 12 that scans light onto the charged photosensitive drum 10 to form a predetermined electrostatic latent image, and a developing unit 13 that develops the electrostatic latent image with toners of four colors, such as, yellow (Y), magenta (M), cyan (C), and black (K). A transfer belt 14 overlaps images of the four colors developed on the photosensitive drum 10 sequentially, a first transfer roller 14a transfers the images developed on the photosensitive drum 10 onto the transfer belt 14, a second transfer roller 14b transfers the overlapped image of four colors on the transfer belt 14 onto a sheet of paper, and a fusing device 15 heats and presses the paper to permanently fuse the transferred image.
The apparatus also includes a photosensitive drum cleaning blade 17, an eraser 18, a conveying path 19 through which the paper is discharged, and a paper cassette 20.
As shown in FIG. 2, the typical paper feeding apparatus of the printer includes a paper cassette 20 that is detachably installed on the main body of the printer to store multiple sheets of paper. The paper cassette 20 includes a knock-up plate 22, on which the paper P is mounted, and lifts up the front edge portion of the mounted paper P. In addition, a semicircular pick-up roller 28 is rotatably installed on the main body of the printer to contact the front edge portion of the uppermost paper P that is lifted by the knock-up plate 22. Therefore, when the pick-up roller 28 rotates, the uppermost paper P enters the main body of the printer through frictional engagement with the pick-up roller 28. The apparatus further includes a paper guide 26 to guide the paper that enters the main body of the printer.
The conventional paper feeding apparatus having the above structure includes a finger unit 24 to prevent paper from being fed in duplicate. The finger unit 24 pressingly supports the front edge portion of the paper P mounted on the knock-up plate 22 to generate a curl at the front edge portion of the paper P when the pick-up roller 28 rotates, thereby separating the uppermost paper P easily.
However, in the typical paper feeding apparatus, the sheets of paper P may be attached to each other due to an electrostatic force between the sheets of paper, thus two or more sheets of paper P can be conveyed even using the finger unit 24.
Accordingly, there is a need for a paper feeding apparatus for a printer that includes a double feed prevention unit to prevent two or more sheets of paper from being supplied simultaneously.